The STEN (or Sten gun) was a family of British 9 mm submachine guns used extensively by British and Commonwealth forces throughout World War II and the Korean War. They were notable for having a simple design and very low production cost making them effective insurgency weapons for resistance groups. STEN is an acronym, from the names of the weapon’s chief designers:Major Reginald V. Shepherd and Harold Turpin, and EN for Enfield.
The STEN Mk II was the most common variation of the STEN made, with over two million units produced. It featured a removable barrel which extended 3 inches beyond the barrel sleeve and a special catch that allowed the magazine and magazine housing to be rotated and lay flat on its side with the weapon.